Reconciliation of CDM abundance and $\mu\to e\gamma$ in a radiative seesaw model

TL;DR

This paper demonstrates that a radiative seesaw model can simultaneously explain neutrino oscillations, dark matter abundance, and comply with lepton flavor violation constraints by appropriately choosing Yukawa couplings and considering coannihilation effects.

Contribution

It shows that the original radiative seesaw model can reconcile dark matter relic abundance with $ ext{BR}(oldsymbol{ ext{mu}} o ext{e}oldsymbol{ ext{gamma}})$ constraints without modifications, through flavor structure and coannihilation.

Findings

Lightest singlet fermion abundance matches WMAP data.

Model remains consistent with $ ext{BR}(oldsymbol{ ext{mu}} o ext{e}oldsymbol{ ext{gamma}})$ bounds.

No need for model modifications beyond flavor structure adjustments.

Abstract

We reexamine relic abundance of a singlet fermion as a CDM candidate, which contributes to the neutrino mass generation through radiative seesaw mechanism. We search solutions for Yukawa couplings and the mass spectrum of relevant fields to explain neutrino oscillation data. For such solutions, we show that an abundance of a lightest singlet fermion can be consistent with WMAP data without conflicting with both bounds of $\mu\to e\gamma$ and $\tau\to \mu\gamma$. This reconciliation does not need any modification of the original radiative seesaw model other than by specifying flavor structure of Yukawa couplings and taking account of coannihilation effects.